The present invention provides a new and improved mold and method of using the mold to cast a plurality of articles.
Heat treatment of single crystal cast articles is facilitated if the articles are solidified with a fine dendritic structure. In an effort to obtain a relatively fine dendritic structure during the casting of the articles, U.S. Pat. Nos. 3,763,926 and 4,108,236 suggest that a large temperature gradient be established as a mold is withdrawn from a furnace. This is done by having the mold immersed in a bath of liquid coolant. To increase the temperature gradient during withdrawal of a mold from a furnace, U.S. Pat. No. 4,108,236 suggests that an insulated baffle be provided between the inside of the furnace and the liquid coolant bath.
The concept of using an annular molten metal distribution system which allows a mold to be completely withdrawn from a furnace past a baffle is disclosed in U.S. Pat. No. 3,810,504. In this patent, an annular array of article molds and the annular molten metal distribution system are supported in the furnace on an annular chill plate. The furnace has a cylindrical outer heater which circumscribes the mold and a cylindrical inner heater which is circumscribed by the mold. During withdrawal of the mold from the furnace, the mold moves downwardly between inner and outer heat sinks. The combination of inner and outer heaters, an annular chill plate, and inner and outer heat sinks results in a relatively complicated apparatus which is difficult to operate and maintain.